Study on the Evaluation of the Abilities for Protection Against the Ultraviolet B Radiation in the Forest Tree Species.

太阳UV-B(紫外线-B辐射，这里取为290-315 nm)的增加预计将是平流层臭氧消耗的结果。本文研究了UV-B辐射对林木生理反应的影响。我们构建了新颖的UV-B辐射系统，该系统可以根据环境UV-B的比例控制补充UV-B的剂量。UV-B的增强水平是环境UV-B的1.3倍。对林木的光合作用能力、气体交换和PSⅡ光化学效率、光合色素和UV-B吸收化合物的组成以及活性氧清除系统中的酶活性进行了检测。由于林木长期暴露在UV-B辐射下，UV-B辐射的增加可能会影响人工林的生产力和天然林的物种组成。Sugi种植园的面积占据了Appr…更明显的是，占所有人工林的45%。为了评估UV-B辐射增加对人工林生产力的影响，我们在苗圃内设置了三个UV-B辐射水平。这些是，使用不同的UV-B辐射系统增强UV-B处理，使用UV切割膜降低UV-B水平和环境UV-B水平。测定了杉木幼树的生理反应。在UV-B强度降低的情况下生长的Sugi幼树的光合作用速率和PSⅡ光化学效率(Fv/Fm)略有增加，而在增强的UV-B水平下生长的树苗与在环境UV-B下生长的树种之间没有显著变化。为了了解UV-B增强对天然林物种组成的影响，我们研究了生长在天然山毛榉(Fagus Crenata)森林中的5种树种的生理反应。奈霸先生。用UV-B切割膜对这5种植物进行了不同水平的UV-B处理。此外，还对生长在自然发生的不同UV-B辐射水平下的幼苗进行了检测。而生长在UV-B水平降低的山毛榉幼苗与周围环境相比，UV-B吸收化合物的含量显著减少，而暴露于强光下的山毛榉幼苗则表现出UV-B吸收色素的增加，其中可能包括高水平的UV-B。叶黄素循环色素的叶绿素含量、叶绿素a/b比值和库大小均发生了变化。由于利用配备UV-B辐射系统的生长室进行的初步实验表明，UV-B吸收色素在山毛榉幼苗中迅速积累，因此观察到的UV-B吸收色素的差异归因于对幼苗生长所在的UV-B水平的适应。因此，生长在田间的山毛榉幼苗似乎具有积累紫外线吸收色素的能力，以响应UV-B水平。但不同UV-B处理的幼苗叶片衰老时间存在差异。UV-B强度越高，叶片衰老的时间越早。虽然五种植物的最大PS II光化学效率没有显著差异，但UV-B吸收色素的最大量在五种植物中都有观察到。虽然种内不同UV-B水平之间的PS II光化学效率差异不显著，但物种内不同UV-B水平之间的紫外光吸收色素的范围和数量存在差异，这些结果表明森林树种有足够的能力来抵御瞬时太阳UV-B辐射的增加。然而，在落叶树种中，如山毛榉，当太阳UV-B辐射增加时，生产期的缩短可能会降低年生产力。较少

Increases in solar UV-B (ultraviolet-B radiation, here taken as 290-315 nm) are expected to result from stratospheric ozone depletion. In this study, the effects of UV-B on physiological responses in forest tree species were examined. We constructed novel UV-B radiation system, which can control the dose of supplemental UV-B in proportion to ambient UV-B. The level of UV-B enhancement was up to 1.3 times that in ambient UV-B. The photosynthetic capacities, such gas exchanges and PS II photochemical efficiency, the composition of photosynthetic pigments and UV-B absorbing compound, the activities of the enzymes in the active oxygen-scavenging system were also examined.Because forest trees are exposed to UV-B radiation on long term basis, the increase of UV-B are likely affected to the productivity in artificial forests and species composition in natural forests.Sugi (Cryptomeria japonica)is one of the most important coniferous species in Japan. The area of sugi plantations occupies appr … More oximately 45% of all the artificial forest. In order to assess the affect of the increased UV-B in the productivity of artificial forest, we designed three levels in UV-B radiation in the nursery. Those were, enhanced UV-B treatments using an UV-B radiation system different, decreased level of UV-B using the UV-cutting films, and ambient level of UV-B. The physiological responses of sugi saplings were examined. While the sugi saplings grown in the decreased UV-B level showed slightly increasing in the photosynthetic rate and PS II photochemical efficiency (Fv/Fm), no significant changes were observed between the saplings in the enhanced UV-B and that in the ambient UV-B.In order to understand the influence of the increased UV-B on the species composition in natural forest, we investigate the physiological responses of the five tree species grown in the natural beech (Fagus crenata) forest Mt. Naeba-san. The five species were treated with different UV-B levels using UV-B cutting films. In addition, the seedlings grown in the naturally occurred different UV-B levels were also examined. While the beech seedlings grown in the decreased UV-B level showed significant decrease in the UV-B absorbing compounds compared with that in the ambient level, the seedlings exposed the strong light, which may include high level of UV-B, showed the increase in the UV-B absorbing pigments. Some changes were observed in the chlorophyll contents, chlorophyll a/b ratio, and the pool size of xanthophyll cycle pigments. Since the preliminary experiment using the growth chambers equipped with UV-B radiation system showed the rapid accumulation of the UV-B absorbing pigments in the beech seedlings, the difference observed in the UV-B absorbing pigments was attributed to be adaptation to the UV-B levels where the seedlings were growing. Therefore, beech seedlings growing in the field seemed to have the abilities to accumulate the UV-absorbing pigments in response to the UV-B levels. However, the differences in the timing of the leaf senescence were observed in the seedlings treated with different UV-B levels. Timing of the leaf senescence was earlier in the seedlings treated with high UV-B level. Although the maximum PS II photochemical efficiency were not significantly changed among the five species, the maximum amount of UV-B absorbing pigments were observed. While the differences in the PS II photochemical efficiency between the different UV-B levels within species were not significantly changed among the five species, differences in the range, of the amounts of UV-absorbing pigments between the different UV-B levels within species were observed.These results suggest that the forest tree species have enough abilities to protect against the increase In instant solar UV-B radiation. In the deciduous tree species, such as beech, however, the shortening of the productive period may decrease the annual productivity when the solar UV-B will be increased. Less